1. Field of the Invention
The present invention relates to an optical disk apparatus that uses an optical pickup to determine whether the chucking of an optical disk is appropriate.
2. Description of the Related Art
An optical disk apparatus includes a turntable rotated by a spindle motor. For an optical disk apparatus having a tray, when an optical disk is placed on the tray, the optical disk is carried into the apparatus and is clamped on the turntable. Then, while the turntable is being rotated rapidly by the spindle motor of the optical disk apparatus, an optical pickup records data, or reproduces data previously recorded, on the optical disk by emitting a laser beam that is focused on the optical disk.
Sometimes, the chucking of the optical disk by the optical disk apparatus is faulty, and the optical disk is chucked in a slanted state. In this case, the optical disk apparatus may not appropriately record or reproduce data on the optical disk. Further, when the chucking performed by the optical disk apparatus is faulty, and an optical disk in a slanted state is rotated rapidly, the optical disk may abut against the disk tray or other internal device portions, and may be scratched or may damage the optical disk apparatus.
Therefore, a conventional device for chucking an optical disk mounted on a turntable notifies a user that a chucking error has occurred, before the turntable is rotated, when it is determined that the optical disk has been incorrectly chucked (e.g., see JP-A-6-187712 (pages 3 to 8, FIGS. 1 to 7)).
To determine a chucking state, the device disclosed in JP-A-6-187712 for chucking an optical disk mounted on a turntable activates a focusing servo for an optical pickup at an initial position facing a lead-in area near the center of the optical disk. As a result, an incorrect chucking state determination may be made.
Specifically, since an optical disk is chucked at its center hole, when the optical disk is held in a slanted state, the distance from the optical pickup is changed more at the outer edge of the optical disk. FIGS. 5A and 5B are diagrams showing the positional relationship between an optical pickup and the recording face of an optical disk that has been inappropriately chucked by an optical disk apparatus. When the optical disk apparatus chucks the optical disk at a predetermined slant angle, as is shown in FIG. 5A, the distance from the optical pickup is not much changed when the optical disk is rotated at the position facing the lead-in area, so that the optical disk apparatus can activate the focusing servo with no problem. On the other hand, as is shown in FIG. 5B, the distance from the optical pickup changes greatly when the optical disk is rotated and the optical pickup is positioned facing the outer edge of the optical disk, so that the optical disk apparatus cannot activate the focusing servo. However, since to determine the chucking state the chucking device disclosed in JP-A-6-187712 actuates the focusing servo at the position facing the lead-in area, even in the case shown in FIG. 5B, the chucking device will determine that the chucking is appropriate.